1. Field
Exemplary embodiments of the present invention relate to an integrated circuit, and more particularly, to an integrated circuit including an NC pad.
2. Description of the Related Art
Diverse integrated circuit chips operate their internal circuits based on an external power supply voltage, which is supplied from the outside. The kinds of internal voltages used in an integrated circuit chip are so diverse that it is difficult to supply all the internal voltages using the external power supply voltage. Therefore, the integrated circuit chip uses an internal voltage generation circuit for generating a voltage whose level is different from that of the power supply voltage in the integrated circuit chip.
Particularly, a charge pump circuit for generating a high voltage that is higher than the voltage level of an external power supply voltage, or a charge pump circuit for generating a negative voltage that is lower than the voltage level of a ground voltage supplied from the outside of the integrated circuit chip is usually used.
FIG. 1 illustrates a conventional integrated circuit chip including a high-voltage pumping circuit 110 and an internal circuit 120 that operates using the high-voltage pumping circuit 110.
Referring to FIG. 1, the high-voltage pumping circuit 110 performs a pumping operation based on a power supply voltage VDD that is applied from the outside of the integrated circuit chip and generates a high voltage VPP which is higher than the power supply voltage VDD. For example, the power supply voltage VDD may be approximately 1.2V and the high voltage VPP may be approximately 4V. The internal circuit 120 operates based on the high voltage VPP generated in the high-voltage pumping circuit 110 and a ground voltage VSS.
Each integrated circuit chip goes through a test operation to figure out its characteristics and whether the integrated circuit chip performs a normal operation or not. When any error is detected in the operation of the internal circuit 120 during the test operation, it may be difficult to determine whether the error is caused by the internal circuit 120 or by the high-voltage pumping circuit 110, e.g., an error in the level of the high voltage VPP. Also, it may be difficult to test the integrated circuit chip by changing the level of the high voltage VPP to figure out the characteristics of the internal circuit 120.